#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    double goal, now = 0;
    int step = 0;
    cin >> goal;
    while (now < goal)
    {
        ++step;
        now += 2 * pow(0.98, step-1);
    }
    cout << step;
    return 0;
}
